Field of the Invention
The present invention relates to a method for producing porous graphite and porous graphite.
Description of the Related Art
Carbon materials such as activated carbon have conventionally been used in the electrodes of various types of batteries and the like by utilizing their high reaction efficiency attributable to their extremely large surface area (see, for example, Patent Document 1). In terms of the performance of electrodes and the like in which carbon materials are used, the negative electrode active material of a lithium ion battery, for example, is required to demonstrate high output, high charge/discharge rate and high capacitor, the electrode catalyst support of a fuel cell is required to demonstrate high output and high durability, while the polarizable electrode of an electric double-layer capacity is required to demonstrate high output and high capacity.
Carbon materials such as activated carbon, carbon black, graphene or carbon nanotubes are used in the electrode catalyst supports, for example, of electrodes and fuel cells. However, since activated carbon and carbon black have low crystallinity and a large number of contact points, they demonstrate high electrical resistance and low electrical conductivity, thereby resulting in the occurrence of the problems of decreased output density and charge/discharge rate due to the occurrence of voltage drops within an electrode. In addition, due to the low crystallinity, there were also problems in terms of decreased corrosion resistance and durability. In addition, although graphene and clusters of carbon nanotubes demonstrate high electrical conductivity and a large specific surface area, due to their small bulk density, the amount of carbon per se that contributes to a battery reaction decreases, resulting in the problem of being unable to generate absolute capacity of a battery.
In order to solve such problems, porous carbon obtained by carrying out sulfonation treatment and carbonization treatment (see, for example, Non-Patent Document 1), and porous carbon obtained by using ultrasonic irradiation and an RF solution having a low catalyst concentration (see, for example, Non-Patent Document 2), have been developed. Since these porous carbons have a large bulk density in bulk and are able to enhance electrical conductivity, they are able to realize comparatively high output and capacity.
Furthermore, a so-called Liquid metal dealloying method was developed by the inventors of the present invention that allows the production of metal members having micropores throughout or in the surface thereof (see, for example, Patent Document 2).